It has become commonplace to use packet communications networks to interconnect digital data users at geographically separated locations. Local area networks (LANs) such as token rings or ETHERNET.RTM. are used to interconnect users within relatively confined localities while wide area networks (WANs) such as the Integrated Services Data Network (ISDN), frame relay networks and cell relay networks such as Asynchronous Transfer Mode (ATM) networks, are used to interconnect users disbursed over a wider geographical area. Indeed, a WAN can be used to interconnect a plurality of LANs. All such communications networks must be supervised, managed and controlled to prevent congestion, to compensate for hardware or software failures, and to meet the quality of service requirements of the users. These requirements involve the detection of network failures, the diagnosis of the problem and the implementation of problem recovery procedures. The system responsible for such problem detection, diagnosis and recovery is commonly known as a network management system. One such network management system is the IBM NetView.RTM. system disclosed in "Planning and Reference for NetView.RTM.--Network Control Program--Virtual Telecommunications Access Method," IBM Form Number SC31-6881-0, December 1989.
The availability of fiber optic transmission media has significantly reduced the transmission error rate in high speed packet networks. The need for self-correcting transmission protocols operating over every transmission link such as X.25 has therefore decreased and faster packet switching protocols such as frame relay are becoming more common. As described in ANSI Standards T1.617-1991 and T1.618-1991 (and the corresponding international CCITT Standards COM XI-R 63-E and COM XI-R 133-E), in the frame relay technology, the user data is packaged in a frame relay frame bounded with delimiter flags and including an address or routing header and a frame error checking trailer. Such frames accept originating user data packets of any size (within limits) at an originating edge node of the packet network, transmit the packets across the frame relay network, and deliver these packets to the user connected to the destination edge node of the packet network. In order to accomplish frame routing, virtual circuits are defined extending from the originating node to the destination node and comprising virtual circuit segments extending between adjacent switching nodes along the route. The physical transmission medium between nodes is assigned, in advance, to a wide variety of virtual circuits, using statistical multiplexing techniques to accommodate a far larger number of virtual circuit segments to the transmission medium that could be accommodated at one time, relying on the bursty nature of digital data traffic. Such virtual circuits can be assigned to dedicated transmission facilities or to switched (dial-up) transmission facilities, and can be assigned permanently to a source-destination pair or assigned dynamically for only the duration of a single connection.
The routing information in the frame relay frame header identifies, at each node, the appropriate virtual circuit segments required to deliver the frame from the source node through the network to the destination node. The same virtual circuit is utilized throughout the duration of the data connection. That is, the assigned segments are always used to complete the particular connection even though bandwidth in the same transmission facilities might simultaneously be assigned as virtual circuit segments to other virtual circuit connections between other users and will be seized, when required, to complete such other connections. When a virtual circuit segment is no longer used by a first virtual circuit connection, the bandwidth is then available for virtual circuit segments of other virtual circuit connections.
Network management services for high speed packet communication networks require the generation of large amounts of information about the status of the virtual circuit segments at each node of the network and the configuration of the switched cross-connections between adjacent virtual circuit segments terminating at the same switching node. Moreover, such status and configuration data must be delivered to the network management system. Such status and configuration information, then, is generated at each of the nodes of the network and delivered, directly or over the network itself, to a network management system attached to one node of the network. In a frame relay network, the status and configuration information from nodes remote from the network management system endnode must be packaged in a frame relay format which can be transmitted across the network to the frame management system. Such management services data has been packaged in a format called a network management vector transport (NMVT). Similar data formats must be provided for network protocols other than the frame relay protocol.
Network management vector transport frames generally comprise a major status vector which, in turn, is comprised of a plurality of status or configuration subvectors each of which includes a plurality of subfields. Each major vector, subvector and subfield is preceded by a header comprising a length field, specifying the length, in bytes, of the corresponding vector, subvector or field, a key field, identifying the information in the vector, subvector or subfield, and the specific status or configuration information itself. Moreover, NMVT major vectors, subvectors and subfields can be repeated a plurality of times in the NMVT, permitting high density packing of management information in the NMVTs.
A large number of major vectors, subvectors and subfields have been defined in "Management Services Major Vectors," System Network Architecture--Formats, Chapter 9, IBM Form Number GA27-3136-11, 12th Edition, May 1991. Adequate information about the status and configuration of the individual virtual circuit segments terminating at a particular node of the network, however, are not provided by the prior art management services vectors. In particular, under prior art network architecture, a virtual circuit extended only for a single segment and there was no need for status and configuration data regarding virtual circuits extending across more than segment between three or more nodes. It is therefore desirable to expand the prior art status information concerning the status of virtual circuit segments.